A Tunisian soldier has been shot dead after opening fire on comrades, killing an officer and two others.

Another 15 soldiers were injured in the attack near the parliament building and a museum attacked by Islamic State militants earlier this year.

The shooting prompted the evacuation of a nearby school and police searched a mosque and cars travelling on the main road, as two military helicopters circled overheard in the aftermath.

It was not immediately clear what caused the shooting at the Bouchoucha barracks in Tunis, but the interior ministry said it did not appear to be a terrorist attack.

Defence ministry spokesman Belhassen Oueslati said the gunman had been killed and confirmed there were other casualties.

Tunisian forces have been on alert since March when the Bardo museum in Tunis was attacked by Islamist gunmen who killed 22 people, mostly foreign tourists.

Since the 2011 uprising against dictator Zine El-Abidine Ben that sparked the Arab Spring across the Middle East, Tunisia has been spared the worst of the chaos seen in neighbouring countries.

But the military have been forced to confront some Islamist hardliners in recent months.